1. Field of the Invention
The invention relates to a percussion tool having a combustion engine.
2. Discussion of the Related Art
Percussion tools such as hammer drills and/or percussion hammer drills having a combustion engine—hereinafter referred to in short as hammer drills—are known in particular as relatively heavy breakers, which are essentially worked vertically in a downward direction. In petrol-powered hammer drills of this kind, a cooling air fan driven via the crankshaft of the combustion engine is provided for cooling the engine. The cooling air fan produces a cooling air flow which is conducted along the outside of the combustion engine cylinder, particularly along the cooling fins provided on the outside of the cylinder. The engine cooling exhaust air discharged from the engine is usually very hot in this case and must therefore be conducted away from the hammer drill by the shortest route.
The percussion mechanism driven by the combustion engine provided to generate the working movement of the hammer drill may also heat up intensely due to the air compression, particularly when a pneumatic percussion mechanism is involved. In order to cool the percussion mechanism, it is therefore known for an additional fan wheel to be provided, which produces a separate flow of cooling air for the percussion mechanism. The appropriate space must be provided for installing this additional fan wheel and design work undertaken.
A rock drill in which a cooling air flow is produced by a cooling air fan is known from DE 866 633 C. The cooling air flow is conducted over ribs to the outer wall of an engine cylinder after which it emerges on the underside of the hood forming the cooling air duct. The problem addressed by the invention is that of specifying a hammer drill and/or percussion hammer drill, in which improved cooling of the components is possible.